A major cause of reduced efficiency in semiconductor devices such as rectifiers is inadequate cooling during normal operation. FIGS. 1 and 2 are perspective and cross-sectional views of a Vishay® Semiconductor brand single phase inline bridge rectifier device 100 having multiple semiconductor dies 106 inside, manufactured by Vishay Intertechnology, Inc. Device 100 is through-hole mountable via leads 112, and includes an exterior epoxy housing 110 that protects the semiconductor dies—during operation of device 100, heat generated by the semiconductor dies is transferred through leads 112 and housing 110. The thermal conductivity of epoxy housing 110 often results in device 100 having poor thermal dissipation performance.
FIG. 3 shows the manner is heat is dissipated in the rectifier device 100 shown in FIGS. 1 and 2. The thermal dissipation route is indicated by the arrows. As shown, the primary heat path extends from the back side of the leads through the epoxy housing 110. In this device the heat dissipation is inhibited by the thickness and low thermal conductivity of the epoxy housing 110. Unfortunately, if the thickness of the housing is reduced to achieve better thermal conduction, molding failures such as IPE or voids 130 (see FIG. 2) tend to increase, leading to problems such as a failure of a high-potential (hipot) test or electric strength test, which is caused by a breakdown in insulation.
Semiconductor device package designs that incorporate additional cooling features have been proposed. International Rectifier Corporation, for example, has created a surface-mountable metal oxide semiconductor field effect transistor (“MOSFET”) chip set referred to as DirectFET™. Certain DirectFET™ devices have a copper can construction, which is advertised to enable dual-side cooling. U.S. Pat. No. 6,624,522 (the “'522 patent”) and U.S. Pat. No. 6,784,540 (the “'540 patent”) describe certain aspects of the construction and/or manufacture of surface-mountable semiconductor devices such as DirectFET™ devices. While these devices address the problem of dissipating heat generated by a power semiconductor device, they do so at the expense of an increase in cost, complexity and/or the overall size of the resulting device.